The correct answer is: B. had lost
The sentence “If Bianca hadn’t argued, Raghubhai had lost the case” is in the past perfect conditional tense. This tense is used to talk about a hypothetical situation that did not happen in the past. The past perfect conditional is formed with the past perfect of the verb “to have” and the past participle of the main verb. In this case, the past perfect of “to have” is “had” and the past participle of “to lose” is “lost”.
The sentence can be paraphrased as follows: “If Bianca had not argued, Raghubhai would have lost the case.” This means that Raghubhai would have lost the case if Bianca had not argued. However, Bianca did argue, so Raghubhai did not lose the case.
The other options are incorrect because they do not agree with the tense of the sentence. Option A, “lost”, is in the simple past tense. This tense is used to talk about events that happened in the past. Option C, “would lose”, is in the simple future tense. This tense is used to talk about events that will happen in the future. Option D, “would have lost”, is in the past perfect conditional tense. This tense is used to talk about hypothetical situations that did not happen in the past.
In conclusion, the correct answer to the question “If Bianca hadn’t argued, Raghubhai . . . . . . the case” is: B. had lost